Jackets, such as windbreakers, sleeping bags for outdoor uses, including hillwalking and hiking, and blousons and coats for town uses, employ woven fabrics with windproof, down-proof, heat-retaining, and lightweight properties. These woven fabrics are usually produced to have air permeability of not more than 1.5 cc/cm2/s.
In recent years, fewer down products use feathers as a filling, in view of animal protection and environmental conservation. Instead, more resin fillings, such as polyester-based, polyolefin-based, or polyphenyl sulfide-based resins, are used. However, the materials used in the resin fillings have poor moisture absorbency by nature and thus, it is difficult to eliminate a damp feeling after sweating as compared to feathers. Furthermore, the resin fillings do not easily allow the fillings to pass through the outer fabric as compared to feathers (hereinafter, a property that the fillings are difficult to pass through is also called “downproof property”). Accordingly, it is not necessary for the air permeability of the outer fabric to be as low as for feathers. Therefore, the outer fabric of a down product containing a resin filling has been required to have increased air permeability to suppress the damp feeling after sweating to some extent.
A highly air-permeable woven fabric is disclosed in, for example, Patent Document 1. Patent Document 1 proposes a woven fabric that has through-holes extending from the front side of the fibers to the back side of the fibers. However, since each of these through-holes is formed as a result that at least a part of the crossover point between warp and weft threads is melted, the through-holes are so large that they are visible to the naked eye and a sufficient downproof property is not demonstrated. In addition, since each of the holes is formed by melting a part of the crossover point, the production of the woven fabric has a high cost and is not suitable for industrial production.
Furthermore, when filaments constituting the woven fabric are displaced from each other when they are rubbed during, for example, washing, the portion in which the filaments are displaced from each other has high air permeability and this may reduce the windproof property and the downproof property of the cloth. Therefore, woven fabrics for the above uses are required to have a property where air permeability does not easily increase even after washing. An example of solving such a problem is shown in Patent Document 2, which discloses a method for producing a down-proof woven fabric obtained by calendering a cloth on one side and thereafter coating a non-solvent urethane resin on at least the other side of the cloth. However, since the woven fabric obtained according to Patent Document 2 is coated with resin, there is a problem in that this method cannot increase the air permeability of the woven fabric.